This invention pertains to improvements in loose leaf binders. The invention provides a simple, economically produced dependable binding mechanism of the split ring variety affording among other advantages, a split ring binder which is not dependent upon a relationship between the binder backbone and the ring binding mechansim.
Binders of the split ring type are extensively used to carry heavy page loads of cummulative reference materials. The rings commonly reach a diameter of three inches and carry such a weight as to severely stress the prongs, the actuating mechanism and the binder covers as well.
In the case of reference materials, many companies utilize binder mechanisms in order to allow the materials to be updated with the incorporation of new, replacement, or supplemental pages. This allows the reference material to be kept current over an extended period of time without replacing enmasse an entire volume. Reference materials held by ring binders are often difficult to photocopy, and persons desiring a photocopy will often remove portions from the ring binder temporarily to facilitate photocopying. Thus, a binding mechanism must be able to withstand periodic opening and closing to facilitate photocopying and incorporation of new material. A binding mechanism must also be able to maintain the binding rings in a tightly closed position during normal use.
Past binding mechansims have not always performed adequately. Over a period of time, which may include years, past binding mechanisms loosen due to wear, material fatigue, and a loss of resiliency in the spring parts. Further, many binding mechanisms were dependent upon the backbone structure of the book or binder for their operation. The binder or book backbone normally is made of a fiber board type of material which over time and wear loses its rigidity, and often does not resist wear of moving parts pressing upon it. Accidental dropping of the book or binding may readily cause damage to the book or binder backbone which will consequently effect the operation of the binding mechanism. Further, the backbone of the binder or book cannot be machined to close tolerances and therefore a great deal of adjustment must be built into the binding mechanism.